Health: Infectious Disease Epidemiology & Prevention Division: Legionellosis

Legionellosis

What is Legionnaires' disease?

Legionnaires' (LEE-juh-nares) disease is a serious type of pneumonia caused by Legionella bacteria that may lead to hospitalization or death. Infection occurs when a person breathes in water droplets from the air (i.e., mist or vapor) that contain the Legionella bacteria. This bacteria is found naturally in freshwater environments and soil but becomes an issue when it grows and spreads inside manmade settings like sinks, showers, humidifiers, etc.

Quick Facts

Did you know there is more than one way to breathe in Legionella bacteria?

Inhalation occurs when a person breathes air into the lungs.

When aerosolized water droplets containing bacteria enter the lungs they can cause a respiratory infection, like Legionnaires' disease.

Inhalation

Aspiration occurs when a person accidentally inhales of food, liquid, or other material into the lungs when swallowing.

If a person aspirates water or ice containing bacteria into the lungs, they can develop a respiratory infection, like Legionnaires' disease.

People can get Legionnaires' disease by breathing in mist containing Legionella bacteria or, in rare cases, by drinking water that contains the Legionella bacteria and it "goes down the wrong pipe" into the lungs.

Healthy individuals may be exposed to the Legionella bacteria but may not become sick. Individuals of higher risk include:

Older people (usually 50 years of age or older)
Those with a chronic lung disease (like COPD or emphysema)
Current or former smokers
Those with a weak immune system from diseases like cancer, diabetes, or kidney failure
People who take medication that weakens the immune system

Symptoms of Legionnaires' disease start about 2-14 days after exposure to the bacteria. Common symptoms include:

Pneumonia
Fever
Chills
Lack of energy
Cough
Muscle aches
Headache
Loss of appetite
Diarrhea and/or vomiting
Shortness of breath

Legionnaires' disease infection happens when a person breathes in water droplets from the air (i.e., mist or vapor) that contain the Legionella bacteria. In general, the bacteria are not spread from one person to another person. Legionella bacteria are also found naturally in freshwater environments and soil but become an issue when they grow and spread inside manmade settings.

Common sources of infection for community and healthcare settings include:

Sinks
Showers
Ice machines
Whirlpool spas / hydrotherapy tubs
Humidifiers
Respiratory therapy equipment
Decorative fountains
Industrial cooling towers

Devices that are NOT a source of infection include home and car AC units.

Lab testing is needed to confirm diagnosis. See your healthcare provider as they may take a sample of lung tissue, urine, or fluid from the lungs to test. Legionnaires' disease is treated with antibiotics (drugs that kill bacteria in the body). Most people who become ill need care in a hospital but make a full recovery. However, about 1 out of 10 people who get Legionnaires' disease will die from the infection.

The key to preventing Legionnaires' disease is to reduce the risk of Legionella growth and spread.

In buildings and public hot tubs - Building owners and managers can use a water management program to help control Legionella.
Keep Reading: About Legionella Control

At home - There are steps people can take to help protect themselves from waterborne germs in their home.
Keep Reading: Preventing Waterborne Germs at Home

In motor vehicles - Legionella can grow in the windshield wiper fluid tank of a vehicle, particularly if the tank is filled with water. To prevent growth and spread of Legionella, only use genuine windshield cleaner fluid and follow the vehicle manufacturer recommendations, if available.
Keep Reading: Legionnaires' Disease among Commercial Vehicle Operators

Legionellosis (Legionnaires' Disease and Pontiac Fever) | CDC

Legionellosis Case Definition | CDC

Classification for Healthcare-associated Cases | CDC

Sampling Procedure and Potential Sampling Sites | CDC

Legionella Environmental Assessment Form | CDC

Patients with risk factors who have prolonged exposure to healthcare settings are at increased risk for developing Legionnaires' disease. Healthcare-associated cases of Legionnaires' disease is a serve pneumonia associated with a 25% fatality rate.

Patient Testing Recommendations -
Keep Reading: Deciding Whom to Test in Healthcare Settings

Water Management Program Toolkit - Healthcare facilities have complex building water systems and often experience construction that impacts systems.
Keep Reading: Developing a water management program to reduce Legionella growth and spread in buildings

Environmental Precautions Recommendations -
Keep Reading: Implementing Control Measures